1kg of fat is equal to 30MJ of energy.the efficiceny of converting fat to energy is 20%. suppose you life a mass of 12kg 2.0m vertically,500 times, how much work do you do?

Question

if all the energy used to do the work comes from the burning fat how much fat is used ?

Answer 1

Work =500mgh=500•12•9.8•2=117600 J.
You need 117600•100/20 =588000 J
1 kg gives 30•10⁶J,
mass of burning fat is
588000/30•10⁶ = 0.0196 kg